A member of the Ukrainian Emergency Ministry searches for bodies close to the site of Thursday's Malaysia Airlines Boeing 777 plane crash near the settlement of Grabovo, in the Donetsk region July 18, 2014.
reuters/Maxim Zmeyev

Local rescue workers have recovered one of two black boxes from near the Malaysia Airlines Flight MH17 crash site, about 25 miles from the Russian border, Reuters reported Friday.

The Australian, citing unnamed Ukrainian officials, said that pro-Moscow rebels may be in possession of the second black box. The officials also reportedly expressed fears that investigations into the crash might be compromised if the black box is sent to Russia or is tampered with. And, because the crash site lies in a territory controlled by pro-Russia separatists, Ukrainian investigators have so far been unable to physically access the region, thereby hindering further investigations, reports said.

According to a report by the Malay Mail, Ukrainian intelligence picked up information that the black box found by the rebels at the crash site in Donetsk would be handed over the border to Russia’s Federal Security Service, or FSB, on Friday.

Pro-Russia rebels from the self-proclaimed Donetsk People's Republic had claimed on Thursday that they had found one of the black boxes and were planning to turn it over to Russian authorities.

The black box, which consists of the flight data recorder and the cockpit voice recorder, stores key technical information about the flight as well as conversations undertaken in the cockpit during a flight. Its recovery can provide essential clues about the fatal crash.

Flight MH17, which was on its way from Amsterdam to Kuala Lumpur, came down near Hrabove, a village in the conflict-hit region near the Ukraine-Russia border, after it was reportedly shot down by a surface-to-air missile.

In a statement posted on its website Friday, the Organization for Security and Cooperation in Europe, or OSCE, said that rebel groups in control of the region had agreed to “provide safe access and security guarantees to the national investigation commission, including international investigators,” adding that “representatives of separatist groups in Donetsk” had agreed to cooperate with the Ukrainian authorities in matters related to “recovery and investigation works.”

An ABC news report, citing an unnamed official, stated that investigators from the FBI and the National Transport Safety Board will head to Ukraine to assist with the investigation.

Liow Tiong Lai, the Malaysian transport minister, also extended the Malaysian government's “full and unqualified support” to the investigation, and said that it would send two “senior accredited representatives” to assist.

Najib Razak, the Malaysian Prime Minister, had earlier announced that he would send a 62 member disaster assistance and rescue team to Kiev.